467372019eng32533425article1------New aspects about the search for the most relevant parameters optimizing SLM materialsWhile the volumetric energy density is commonly used to qualify a process parameter set, and to quantify its influence on the microstructure and performance of additively manufactured (AM) materials and components, it has been already shown that this description is by no means exhaustive. In this work, new aspects of the optimization of the selective laser melting process are investigated for AM Ti-6Al-4V. We focus on the amount of near-surface residual stress (RS), often blamed for the failure of components, and on the porosity characteristics (amount and spatial distribution). First, using synchrotron x-ray diffraction we show that higher RS in the subsurface region is generated if a lower energy density is used. Second, we show that laser de-focusing and sample positioning inside the build chamber also play an eminent role, and we quantify this influence. In parallel, using X-ray Computed Tomography, we observe that porosity is mainly concentrated in the contour region, except in the case where the laser speed is small. The low values of porosity (less than 1%) do not influence RS.Additive Manufacturing10.1016/j.addma.2018.11.0232214-8604http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=Alerting&SrcApp=Alerting&DestApp=WOS_CPL&DestLinkType=FullRecord&UT=WOS:00045637880003107.02.2019Tatiana MishurovaK. ArtztJ. HaubrichG. RequenaGiovanni BrunoenguncontrolledAdditive manufacturingenguncontrolledSelective laser meltingenguncontrolledResidual stressenguncontrolledComputed tomographyIngenieurwissenschaften und zugeordnete Tätigkeiten8 Zerstörungsfreie Prüfung8.5 Mikro-ZfPMaterialMaterialien und StoffeVerlagsliteraturVolltext-PDF im Netzwerk der BAM verfügbar ("Closed Access")474282019eng261, 11329article1------Exploring the correlation between subsurface residual stresses and manufacturing parameters in laser powder bed fused Ti-6Al-4VSubsurface residual stresses (RS) were investigated in Ti-6Al-4V cuboid samples by means of X-ray synchrotron diffraction. The samples were manufactured by laser powder bed fusion (LPBF) applying different processing parameters, not commonly considered in open literature, in order to assess their influence on RS state. While investigating the effect of process parameters used for the calculation of volumetric energy density (such as laser velocity, laser power and hatch distance), we observed that an increase of energy density led to a decrease of RS, although not to the same extent for every parameter variation. Additionally, the effect of support structure, sample roughness and LPBF machine effects potentially coming from Ar flow were studied. We observed no influence of support structure on subsurface RS while the orientation with respect to Ar flow showed to have an impact on RS.We conclude recommending monitoring such parameters to improve part reliability and reproducibility.Metals10.3390/met90202612075-4701urn:nbn:de:kobv:b43-474281http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=Alerting&SrcApp=Alerting&DestApp=WOS_CPL&DestLinkType=FullRecord&UT=WOS:00046076470015228.03.2019Creative Commons - CC BY - Namensnennung 4.0 InternationalTatiana MishurovaK. ArtztJ. HaubrichG. RequenaGiovanni BrunoenguncontrolledAdditive manufacturingenguncontrolledSynchrotron X-ray diffractionenguncontrolledResidual stressenguncontrolledTi-6Al-4VIngenieurwissenschaften und zugeordnete Tätigkeiten8 Zerstörungsfreie Prüfung8.5 Mikro-ZfPMaterialDegradation von Werkstoffen und MaterialienVerlagsliteraturVolltext-PDF für die Öffentlichkeit verfügbar ("Open Access")Wissenschaftliche Artikel der BAMBundesanstalt für Materialforschung und -prüfung (BAM)https://opus4.kobv.de/opus4-bam/files/47428/Mishurova-metals-09-00261.pdf